In Long Term Evolution (LTE), until Release 13, all Reference Signals (RSs) that a User Equipment (UE) uses for Channel State Information (CSI) calculation, such as Cell specific Reference Signal (CRS) and CSI Reference Signal (CSI-RS), were non-precoded such that UE is able to measure the raw channel and calculate CSI feedback including preferred precoding matrix based on that the RS. As the number of Transmit (Tx) antenna ports increases, the amount of feedback becomes larger. In LTE Release-10, when closed loop precoding with 8 Tx was introduced, a two-stage precoder approach was introduced where UE first selects a wideband coarse precoder and then selects a second precoder per subband. Another possible approach is that network beamforms the CSI-RS and UE calculates CSI feedback using the beamformed CSI-RS. This approach was adopted in LTE Release 13 as one option for the Full Dimension Multi-Input Multi-Output (FD-MIMO) operation as described in the next section. Improvements in reference signals are needed.